1. Field of the Invention
The present invention relates to a vacuum processing apparatus that includes a robot for use in substrate transfer, and a substrate transfer method and, more particularly, to a vacuum processing apparatus that includes a robot for use in substrate transfer in, for example, an in-line deposition apparatus which deposits a layer on a recording medium having a center hole, such as a magnetic disk or an optical disk, and a substrate transfer method using the robot.
2. Description of the Related Art
A robot has conventionally been employed to pick up substrates before a predetermined deposition process from a substrate storage unit and load them onto a carrier, or to unload the substrates having undergone the predetermined deposition process from the carrier and store them in a substrate storage unit.
A scalar robot is widely used as a robot which performs this operation. An example is a robot including a first arm and second arm whose driving is controlled via a driving unit body and a driving belt, and an adapter at the distal end of the second arm. This adapter is provided with end effectors which have various shapes and can hold substrates, and therefore can transfer the substrates (see, for example, Japanese Patent Laid-Open Nos. 8-274142 and 2001-210695).
An end effector of a robot described in Japanese Patent Laid-Open No. 8-274142 can transport two substrates at once, and sequentially load substrates onto a carrier which can mount two substrates. Also, an end effector of a robot described in Japanese Patent Laid-Open No. 2001-210695 uses an arched end effector to allow an operation of transporting two substrates at once and loading these substrates onto a carrier at once, thereby improving the throughput.
Unfortunately, in each of the robots disclosed in Japanese Patent Laid-Open Nos. 8-274142 and 2001-210695, substrate holding becomes unstable upon raising its operating speed in excess of a predetermined speed. Also, each of these robots inevitably requires more frequent maintenance with a rise in operating speed.